Tuesday, August 8, 2023

Carroll Trashes Copenhagen Interpretation

Physicist Sean M. Carroll posted his monthly AMA, and he answers a question about interpretations of quantum mechanics.

He trashes the Copenhagen interpretation as being too vague and incoherent to be worthy of serious consideration.

He says he favors the many-worlds interpretation, and then Bohmian mechanics as a distant second. He is so strongly in favor of many-worlds, that he says it is not worth time thinking about interpretations.

This opinion is so crazy that it discredits much of what he says.

Copenhagen is what the textbooks teach. We have about a trillion dollar sector based on QM, notably semiconductors and lasers, and it all uses Copenhagen. If that is not a scientific theory worthy of consideration, then something is wrong with your definition of theory.

No one has ever used many-worlds or Bohmian to do a practical QM calculation. That is, $0 based on it.

He is like someone saying that everyone should use teleportation for transportation, because cars do not meet his definition of a vehicle.

In other podcasts, he argues that MWI is the most testable, because it could be refuting by refuting the Schroedinger equation. This is wrong because those textbook applications of QM use that equation, but do not use many-worlds. His many-worlds are not observable, so no one could ever say whether they obey equations or not.

He previously had a long rambling over-opinionated podcast on whether there is a crisis in Physics. I tried to listen, but it was boring and stupid.

Here is a recent paper on How Bohr's Copenhagen interpretation is realist and solves the measurement problem. It looks at what Bohr actually said and wrote, and says he did not believe that Schroedinger's cat was really in a superposition of alive and dead states, or some of the other views attributed to him, and that he had a sensible view of the real world.

https://youtu.be/U2JtJpSDdys?t=1845

11 comments:

  1. If you don't know how something works, invoking an infinite number of universes to get around the fact is not exactly a testament to your problem solving skills.

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  2. Copenhagen is trash. Field theory has succeeded QM and allowed the derivation of things like the Pauli Exclusion Principle. There are classical analogs to just about everything.

    There exist classical analogs to Hawking and Unruh radiation.

    As pointed out by Arnold Neumaier, George Stokes, in 1852, "described all the modern quantum phenomena of a single qubit, explaining them in classical terms," including spin-1/2 systems. It appears that ALL quantum systems can be simulated by classical electromagnetic waves.

    Sean Carroll rightly pointed out that "[t]he Klein-Gordon and Dirac equations are actually not quantum at all — they are classical field equations, just like Maxwell’s equations are for electromagnetism and Einstein’s equation is for the metric tensor of gravity."

    Quantum collapse can be explained by non-linearity of particle creation/annihilation. The non-linearity is rooted in existing physics of field interactions. Note: Collapse is not instantaneous.

    Lazaro and Link describe spin-1/2 systems in terms of a quaternionic mechanical system.

    Quantum tunneling can be easily described in a classical way, when objects have extent.

    I have documented many classical analogs of quantum entanglement and the violation of Bell inequalities, including Brownian motion, chaotic balls, Ising models, classical optics and water waves. Supercorrelation is just conditional probability on background fields.

    Considering stochastic QFT, SED provides a classical explanation for a number of different quantum effects.

    GR is already classical. Scharf, following Einstein and Weinberg, gave a non-geometrical version of gravity that mainly acts as a classical field, although derived from a quantum gauge field. When attempting non-geometrical field theory unifications, few even consider Bondi radar.

    Quantum computers are just analog computers. An appeal to the Turing complexity of quantum computers is circular. Gil Kalai has made arguments against their realization in terms of the harmonic analysis of Boolean functions, but I would suggest it's underlying "analog" behavior that limits their realization. Spin is continuous, there's no "global phase" and amplitudes interfere, not probabilities. Furthermore, E-T uncertainty and Boltzmann's law put a strict lower bound on QC runtime. A cold computer is a slow computer. Landauer's limit ignores quantum fluctuations.

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    Replies
    1. > ``Quantum collapse can be explained by non-linearity of particle creation/annihilation. The non-linearity is rooted in existing physics of field interactions. Note: Collapse is not instantaneous.''

      Could you please give details and references to research papers/books for each of these three statements? Thanks in advance.

      Best,
      --Ajit

      Delete
  3. Yeah absolutely bizarre. How can something be used for coming on hundred years with success after success and be "hopelessly vague".
    When one goes to QFT things get even further from classical style thinking. See for example how infrared divergences are handled in QFT, namely one must compute the chance a detector is excited not the chance that an electron arrives at a location in some measurement device independent way. Only the former comes out as finite, with an explicit dependence on the detectors sensitivity.
    Physics moved on from views like Carroll's since 1925. Absolutely daft that most physicists in the public view now argue against QM.

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    Replies
    1. Hi Darran,

      > `` See for example how infrared divergences are handled in QFT, namely one must compute the chance a detector is excited not the chance that an electron arrives at a location in some measurement device independent way. Only the former comes out as finite, with an explicit dependence on the detectors sensitivity.''

      Yes, in my iqWaves approach, though it escaped my attention while writing down my first conference paper on it, Detectors are active devices not passive, though your description that the detector is ``excited'' seems to fall short a bit.

      But the reason I [ahem, ahem] took the trouble to write this comment is the following: I appreciated knowing, for the first time in my life, that ``Only the former comes out as finite, with an explicit dependence on the detectors sensitivity.''

      As a systemically unfunded, unaffiliated, and in any case non-Brahmin an Indian, I don't expect you to reveal your real name to me, let alone consider collaborating with me. This note, just to let you know that I would be willing, should you be, what else, willing.

      Best,
      --Ajit

      Delete
    2. Ajit,

      The detector being "excited" is a common technical term, it's not my own personal "literary" attempt at a description.

      Delete
    3. Roger,

      Yes, I meant the term ``excited'' in its technical sense.

      Any random idiot's description that the detector is merely ``excited'' falls short. In fact, it exponentially falls short, even if it comes from a Nobel laureate or a few [*].

      If a description falls too short, it falls too short. Are there any two ways about it?

      If a Swiss Alps hill station doesn't have the beauty of Mahabaleshwar, it doesn't have it, full stop. [And, may be, vice versa, too!] Are there any two ways about it [just to get into more literary and artistic etc. territories]?

      Best,
      --Ajit
      [*] Shoot me an email, Roger, or others who write with their real names, to know why I say so --- even as I am in the midst of building up my theory.

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    4. Ajit,

      This seems a bit over the top. "Excited" just means the detector activated in a statistically significant way, i.e. it wasn't noise.

      Those are the only types of events QED assigns probabilities to. It's simply a property of the theory. I have no idea how it "falls short". It's just a word for detector events that aren't noise.

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    5. Nope. The kind of events to which probabilities are assigned isn't much interesting from a *theoretical* viewpoint, whether the theory is NRQM, or QED/RQM. It's the ontological viability of what your mainstream QED posits as "events".

      MS QED (QFT) "happily" has too many constructs about whose ontology it is "happily" ignorant.

      (Aside: Recall your Californian Richard Feynman's "Matador"-like van.)

      My set of theoretical concepts do not.

      Wait for a few months (up to a year or so, may be more) for my theory paper; thanks but no thanks, in advance, dear Roger!

      Best,
      --Ajit

      Delete
    6. Change:

      " It's the ontological viability of what your mainstream QED posits as "events"."
      to:

      "It's the ontological viability of what your mainstream QED posits as the *intermediate* "events".
      "
      Best,
      --Ajit

      Delete